Non-woven fibre product comprising fibres of recycled material

ABSTRACT

The present invention concerns an air-laid non-woven fibre product comprising recycled material and manufactured by a dry forming process, said product comprising: a first portion of up to 99% dust material, where the dust material is preferably recovered dust from manufacturing or the like of fibrous textile material, preferably cotton textiles, and a second portion at least 1% bi-component fibres having a length between 2-75 mm, preferably 2-25 mm in length.

All patent and non-patent references cited in the present applicationare also hereby incorporated by reference in their entirety.

The present invention relates to a non-woven fibre product comprisingrecycled material and manufactured by a dry forming process, a method ofmanufacturing such product and the use of such recycled materials.

From U.S. Pat. No. 5,516,580 an insulation batt is known, where thematerial contains a portion of cellulose fibres, and longer bondingsynthetic fibres. These synthetic fibres are so-called bi-componentfibres that have an outer sheath which is heat-fused with outer sheathsof other synthetic fibres at crossing contact points thereof to form amatrix having pockets for retaining loose fill cellulose fibres therein.This matrix eliminates the need of an adhesive binder to retain thecellulose fibres in the matrix.

The drawback of this insulation board is that the fibre batt obtainedhereby is not particularly resilient and the use of longer bi-componentsynthetic bonding fibres makes the product very expensive tomanufacture.

A method of making a resilient mat is known from U.S. Pat. No.5,554,238. The insulation mat according to this method comprisescellulosic and thermoplastic fibres. A mat is formed in an air-layingprocess and subsequently the surface is flame-treated to melt thethermoplastic component on the surface forming a skin which keeps thecellulosic fibres intact. The thermoplastic fibres in the interior ofthe mat remains unmelted, whereby the mat is provided with a spring-backcharacteristic, which allows the mat to retain most of its originalshape after it has been compressed, e.g. for shipping.

However, this resilient mat has a “crisp” exterior surface reducing theresiliency of the mat as a whole and not homogeneously bonded throughoutthe product, which does not allow for easy handling since the productmay easily delaminate or otherwise break up. The insulation effect ismoreover reduced due to the more compact structure of the fibre product.

From WO 01/48330 a recyclable insulating mat comprising shredded wastepaper or cardboard mixed with natural fibres and 5-50% polyester isknown.

In DE 196 02 551 C1, there is described a mat for manufacturingself-supporting form parts by heat treatment. The mat comprises longnatural fibres and thermoplastic binding means provided as syntheticfibres. The thermoplastic binding means are provided synthetic materialwith a high melting point and a low melting point.

It is an object of the present invention to provide a resilient fibrousproduct which is recyclable and inexpensive to manufacture from wastematerial.

This object is achieved by a non-woven fibre product comprising recycledmaterial and manufactured by a dry forming process, said productcomprising a first portion of up to 99% dust material, where the dustmaterial is preferably recovered dust from manufacturing or the like offibrous textile material, preferably cotton textiles, and a secondportion at least 1% bi-component fibres having a length between 2-75 mm,preferably 2-25 mm in length.

Dust material from processing textile materials, from e.g.manufacturing, cutting, tumble drying and recycling of textiles, a wasteproduct is dust which is frequently removed from filter screens and thelike in the processing equipment. This dust is at present disposed ofand shipped off to landfill or burned off. A textile processing businessthus is faced with costs for removing and disposing of this dustmaterial. However, according to the invention, the use of dust materialis advantageous because there is now provided a product in which thiswaste material can be recycled and used for a useful purpose. Thenon-woven product obtained by the invention has excellent spring-backproperties and is very inexpensive in manufacturing since the keyingredient, i.e. the dust material, is inexpensive in purchase. The dustmaterial from textile processing are characteristic in that the textilefibres are very short and crimped since the fibres derive from yarnsthat are spun and subsequently woven and thereby provided with aspring-like, crimpy shape. By the invention it is thus realised that anairy, non-woven product is obtainable which has a very low density andwith good insulation properties. The fibre mat products may accordinglybe used for heat or sound insulation purposes, such as insulation in thehousing sector, the automotive sector or for maritime purposes as wellas within product types such as air condition equipment, machinery, windturbines etc.. Accordingly, it is realised that the products may beprovided in predetermined shapes to fit within or around panels or thelike.

It is realised that by a dry-laid, air-laid or otherwise fibre formedproduct according to the invention a cost-effective fibrous, softproduct of recycled materials can be provided in a predetermined shapewhich can be used in the packaging industry as a substitute for foamproducts or the like which are otherwise used for protecting goods, suchas electronic products, etc. inside the package.

According to a second aspect of the invention, there is provided amethod of manufacturing a non-woven product by dry forming a product offibrous material, said method comprising the steps of:

-   -   providing a fibre mixture for providing a fibrous material,        where said fibrous material comprises a first portion of up to        99% dust material, where the dust material is preferably        recovered dust from manufacturing or the like of fibrous textile        material, preferably cotton textiles, and a second portion at        least 1% bi-component fibres having a length between 2-75 mm,        preferably 2-25 mm in length and comprising a core and an outer        sheathing, said outer sheathing having a first melting        temperature which is lower than the second melting temperature        of the core;    -   advancing said fibrous material into a forming medium,    -   heating the web of fibres formed on the forming wire to a        temperature above the first melting temperature; and then    -   advancing the fibrous web through a pressing section whereby a        fibrous product web with a predetermined density is formed.

By the invention, it is realised that the textile dust material can berecycled in an advantageous manner by utilising this material in anair-laid fibre mat which is obtainable by using the manufacturingtechnology disclosed in WO2005/044529. However it is realised that otherdry-laying web forming processes may be used. Accordingly, an aspect ofthe invention involves the use of recyclable dust material for such anair-laid product as mentioned above by performing the method describedabove.

The fibre mat product according to the invention is furthermoreadvantageous since the product is resilient with spring-back properties,i.e. that the mat raises again after compression and resumes itsoriginal shape.

This advantageous characteristic of the product according to theinvention is also enhanced by the use of bi-component fibres so that theresulting fibrous mat is very flexible as the bi-component fibres actingas binding means in the product are short. The bi-co fibres become hardwhen cured after having been heated above the melt temperature, so byusing short bi-co fibres the bi-co fibres do not adversely affect theresulting product with respect to flexibility and elastic propertieswhen cured due to their short length.

Moreover, it is realised by the invention that the bi-component fibresmix better with the recycled dust material fibres because of the shortand/or crimped nature of the fibres whereby only a small proportion ofbi-co fibres are needed to provide sufficient coherence of the product.This further enhances the flexibility of the fibrous product.

In a preferable embodiment of the invention there is provided a thirdportion of shredded textile material, such as recycled fibres fromtextile materials of so-called shoddy obtained by shredding the recycledtextile material into fibres.

According to a preferred embodiment, at least 50% of the portion ofbi-component fibres is crimped fibres with a length between 2 to 50 mm.By using short and crimped fibres, e.g. of a helical shape extraflexibility and resilience is achieved in the product allowing theproduct to appear softer and having good properties with respect toraising again after compression and resuming its original shape. It isalso realised that the bonding fibres may be bi-component fibressubstituted or supplemented with polyester fibres, polypropylene and/orother plastic fibres having bonding characteristics.

At least the first portion of fibrous material may preferably beprovided with an additive. Accordingly, at least the third portion ofshredded textile fibres may be impregnated with a material for wettingthe third portion of fibrous material. Moreover, at least the firstportion of fibrous dust material may be impregnated with a material forwetting the dust material. By impregnating the fibres prior to theheating, the resulting effect is found surprisingly advantageous. Thefibres become crispy during the heating which in turn means that theresulting fibre mat product becomes easy to cut into a predeterminedshape afterwards.

In an embodiment, the fibres are provided with fire-retarding chemical,such as Borax, Boric acid, Ammonium sulphate or aluminium sulphateand/or citrus based compounds, mixed with, sprayed onto or impregnatedinto the fibres either before, during or after the forming process, e.g.in the forming box before being laid on the forming wire. In anotherembodiment, the dry-formed fibre mat may be sprayed with fire-retardingchemical, e.g. after the mat is formed and heated.

In an advantageous embodiment, the fibre portion of dust material and/orthe third portion of shredded textile fibres, such as shoddy, areimpregnated before being advanced into the forming box. The impregnatingmaterial is preferably a fire-retarding chemical in liquid or powderform. Hereby, the individual fibres are saturated utilising that thenature of the fibres is that they are absorbent. This provides anefficient fire-retarding characteristic of the finished product sincethe fire retarding chemicals are absorbed in the fibres. Thefire-retarding chemical may be in liquid or powder form.

It is found that the dry-laid fibre product can be produced with agrammar weight between 8 kg/m³ and 200 kg/m³, in particular between 8kg/m³ to 20 kg/m³.

If extra bonding of the fibres is required, an additional fluidizedbinder may be sprayed into the forming box and onto the fibres therein.The fluidized binder may alternatively be sprayed onto the fibres. As afurther alternative or as a supplement, binder in pulverised form may bemixed with the fibres before the mixture is forwarded to the formingbox.

The invention is further explained with reference to the accompanyingdrawings which show diagrams of three embodiment of the manufacturingprocess for producing a product according to the invention.

With reference to the drawings, three examples of the invention areshown and described in the following:

A first portion of dust material recovered dust from manufacturing orthe like of fibrous textile material, preferably cotton textiles, isprovided. This dust material is a waste product in most textileprocessing operations and contains typically very short cotton fibres.

These fibre portions are mixed with a small second portion ofbi-component fibres. These bi-component fibres comprise a core and anouter sheathing, said outer sheathing having a first melting temperaturewhich is lower than the second melting temperature of the core. Thepurpose these bi-component fibres serve is to provide bonding betweenthe fibres in the first portion of fibres. The bi-component fibresbecome hard when cured after having been heated above the melttemperature, so by using short bi-co fibres the bi-co fibres do notadversely affect the resulting product with respect to flexibility andelastic properties when cured due to their short length. Moreover, theshort bi-component fibres blend very well with the fibres of the firstportion ensuring a more homogeneous bonding throughout the product.

A third portion of waste material in the form of a shoddy, i.e. shreddedtextile material, predominantly comprising cotton fibres may also beprovided as a portion for the air-laid product to be manufactured. Thisso-called shoddy material originates from fabric, such as garment,shredded into yarns of about 10-125 mm fibres. The shredded textilefibres will naturally contain an amount of dust material. This amountmay be increased by providing a pre-treatment of the shredded textilefibres, such as a further shredding prior to the fibre mixture.

The mixture of fibres are forwarded to a forming box, preferably of thekind described in WO2005/044529, where the box is provided with arevolving belt screen allowing for an even distribution of fibresirrespective of their size.

The fibres are introduced into the forming box and laid on the formingwire beneath the forming box. The web of fibres is forwarded in acontinuous motion through a heating station where the bi-componentfibres are activated and the fibrous web is provided with its coherence.

During the heating process, the fibre mat is subjected to a heat ofapproximately 130° C. for a predetermined amount of time, such as 5 sec.to 5 min, whereby the bi-co fibres are activated.

The web is then cured as the heated bi-component fibres are cooled andthe web may be forwarded through a pressing station for providing theresulting mat product with a predetermined density. Hereby, a costeffective fibre product having a grammar weight of 8-200 kg/m³ isprovided, which has a good spring elastic effect and insulationproperties.

The fibrous web may be sprayed with a fire-retarding substance, such asBorax, Boric acid, Ammonium sulphate or aluminium sulphate, forproviding the product with fire-retarding properties. Alternative tospraying the formed web, this substance could also be sprayed into theforming box and thereby priming the fibres before the fibres are laidonto the forming wire.

In order to achieve a superior fire-retarding characteristic of theair-laid product, it is realised by the first portion of dust materialmay be treated with the fire-retarding chemical or other types ofadditives prior to the fibre mixing, cf. FIG. 2. Likewise, is itpossible to treat the shredded textile fibres material before the fibremixing, cf. FIG. 1 or it is possible to treat both textile fibreportions with fire retarding chemicals before the mixing of the fibres,cf. FIG. 3. The advantage being that the fire-retarding chemical isabsorbed into the fibres. As indicated in FIG. 3, an additive, such as afire-retarding chemical or other functional additives may be applied tothe product either immediately before or during any of the processingsteps.

It is furthermore realised that a portion of fruit or grain shells, suchas rice shells or the like, can be added to the fibre mixture. Thisresults in an airy product with robust properties.

By the present invention, it is realised that the variations of theabove-mentioned example may be performed without departing from thescope of the invention as defined in the accompanying claims. Forinstance a portion of cellulose fibres or other types of fibres may beprovided depending on which properties of the fibre product is required.

1.-20. (canceled)
 21. A non-woven fibre product comprising recycledmaterial and manufactured by a dry forming process, said productcomprising: a first portion of up to 99% dust material, where the dustmaterial is recovered dust from manufacturing or the like of fibroustextile material, and a second portion at least 1% bi-component fibreshaving a length between 2-75 mm.
 22. A product according to claim 21,wherein there is provided a third portion of shredded textile material,comprising recycled fibres from textile materials of so-called shoddyobtained by shredding the recycled textile material into fibres.
 23. Aproduct according to claim 21, wherein at least 50% of the portion ofbi-component fibres are crimped fibres with a length between 2 to 50 mm.24. A product according to claim 21, wherein at least the first portionof fibrous material is provided with an additive, and at least the firstportion of fibrous dust material is impregnated with a material forwetting the dust material.
 25. A product according to claim 22, whereinat least the third portion of shoddy is impregnated with a material forwetting the third portion of fibrous material.
 26. A product accordingto claim 24, wherein the impregnating material is a fire-retardingchemical in liquid or powder form.
 27. A product according to claim 26,wherein the fire-retarding chemical is selected from a group comprisingborax, boric acid, ammonium sulphate or aluminium sulphate and/or citrusbased compounds.
 28. A product according to claim 21, wherein thedry-formed fibre mat is provided with fire-retarding chemical in liquidor powder form.
 29. A product according to claim 21, wherein the grammarweight of the air-laid product is between 8 kg/m³ and 200 kg/m³.
 30. Amethod of manufacturing a non-woven product of the kind mentioned inclaim 21 by dry forming a product of fibrous material, said methodcomprising the steps of: providing a fibre mixture for providing afibrous material, where said fibrous material comprises a first portionof up to 99% dust material, where the dust material is recovered dustfrom manufacturing or the like of fibrous textile material, preferablycotton textiles, and a second portion at least 1% bi-component fibreshaving a length between 2-75 mm, preferably 2-25 mm in length andcomprising a core and an outer sheathing, said outer sheathing having afirst melting temperature which is lower than the second meltingtemperature of the core; advancing said fibrous material into a formingmedium to form a web of dry-laid fibres; heating the web of fibresformed on the forming wire to a temperature above the first meltingtemperature; and advancing the fibrous web through a pressing sectionwhereby a fibrous product web with a predetermined density is formed.31. A method according to claim 30, whereby a fluidized binder issprayed into the forming box and onto the fibres therein.
 32. A methodaccording to claim 30, whereby there is supplied a third portion ofshredded textile material, comprising recycled fibres from textilematerials of so-called shoddy obtained by shredding the recycled textilematerial into fibres and/or cellulose fibres.
 33. A method according toclaim 30, whereby at least the first portion of fibrous material isprovided with an additive.
 34. A method according to claim 30, wherebyat least the third portion of shoddy is impregnated with a material forwetting the third material portion.
 35. The use of fibrous dust materialrecovered from textile material processing equipment in a non-wovenfibre product according to claim
 21. 36. The use of fibrous dustmaterial recovered from textile material processing equipment in anon-woven fibre product according to claim 30.